The colors that are used to draw the interior area of non-pixmap icons
on a icon-drawing-view in a
chart-or-plot. The value
should be a sequence (list or vector) of RGB objects
(see make-rgb) and/or symbols
that are globally bound to RGB objects. The default value is a list
returned by the following (see make-rgb for a list of predefined colors):

If the value is nil,
then black is used to
fill all icons. Otherwise, the first object in the chart-or-plot's
sequence of chart-objects is
drawn with the first fill color, the second object with the second
color, and so on. If there are fewer colors in the list than there
are chart-objects, then the
drawing code will cycle back through the list of colors as needed.